The present invention relates to a sprinkler or spray nozzle for on-site fire-extinguishing systems with at least one outlet opening 6 that determines the flow of liquid fire-extinguishing agent in accordance with the pressure on the agent and with or without a downstream deflector 4.
Stationary fire-extinguishing systems are employed to prevent damage from conflagrations in large structures such as department stores, industrial plants, warehouses, garages, etc. The density of the pipeline network depends on local ordinances. Sprinklers, as employed herein also intended to embrace fire-extinguishing nozzles are positioned at the ends of the pipeline.
Sprinkler nozzles of the type known from German patents Nos. 2 428 446, 2 539 703, 2 639 245, and 2 716 544 for example are manufactured worldwide today mainly in the three sizes K 57, K 80, and K 115, with outflow cross-sections of approximately 0.7, 1.0, and 1.4 cm.sup.2 respectively, and more rarely in other dimensions. The flow constant K represents the water-outflow rate Q in liters per minute at 1 bar of above-atmospheric pressure upstream of the sprinkler. K can also be expressed in other units. In this case the values become different since the sprinklers are intended to function at above-atmospheric pressures ranging from at least approximately 0.5 bar to approximately 5 bar, the actual water-outflow rate of a sprinkler of current design can be obtained from the formula ##EQU1## wherein
Q=flow rate in liters per minute
K=flow at an above-atmospheric pressure of 1 bar, and
p=above-atmospheric pressure upstream of the sprinkler.
The effect of how fast the water is supplied is ignored here because any errors that derive from it are negligibly small given the pipe dimensions and flow rates prevailing in sprinkler systems.
Since pipes of unequal length lead from the water-supply line to the individual sprinklers or fire-extinguishing nozzles in fire-extinguishing systems of this type, the pressure losses in the pipes and hence the pressures at the individual sprinklers or fire-extinguishing nozzles will differ. The water-supply lines and pipelines are accordingly dimensioned to ensure that--even in the worst possible case, when all the sprinklers or fire-extinguishing nozzles in the operational area (the area over which all the sprinklers or fire-extinguishing nozzles have to be adequately supplied with water) are completely open--there will be sufficient pressure for unobjectionable function even at the sprinkler or fire-extinguishing nozzle at the end of the longest length of piping and accordingly subject--due to the greatest pressure drop--to the lowest pressure in the system.
Since all the other sprinklers in the system will accordingly be subjected to higher-than-necessary pressure and will accordingly experience greater flow than the worst-located sprinkler, the amount of water exiting over the total operational area will always be greater than theoretically necessary for the system. Thus degrees of non-uniformity of around 140% or more of the theoretically requisite amount of water are common, and pumps, pipelines, reservoirs, power, etc. must be installed to handle the excess. This makes the equipment more extensive and costly.